Fix docs and package name after jaydiff refactor

Update README title and import examples from old `diff` module name to
`jaydiff`. Align pyproject.toml package name and include pattern to match
the renamed package directory.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -1,4 +1,4 @@
-# jay-diff
+# jaydiff
 
 Lightweight JSON diff / patch library for Python.
 
@@ -36,7 +36,7 @@ All operations are recursive — nested dicts are handled at every depth.
 ## Usage
 
 ```python
-from diff import jay_diff_full, jay_merge_full
+from jaydiff import jay_diff_full, jay_merge_full
 from copy import deepcopy
 
 old = {'soc': 80, 'range': 300, 'status': {'charging': True}}
@@ -54,7 +54,7 @@ assert result == new
 When a key whose value is a dict is absent from `new`, the delete delta records `None` to signal "remove the entire key":
 
 ```python
-from diff import jay_diff_del
+from jaydiff import jay_diff_del
 
 jay_diff_del({'a': 1, 'b': {'x': 1, 'y': 2}}, {'a': 1})
 # {'b': None}

pyproject.toml

@@ -3,10 +3,10 @@ requires = ["setuptools>=61"]
 build-backend = "setuptools.build_meta"
 
 [project]
-name = "jay-diff"
+name = "jaydiff"
 version = "0.1.0"
 description = "Lightweight JSON diff / patch library"
 requires-python = ">=3.10"
 
 [tool.setuptools.packages.find]
-include = ["jay_diff*"]
+include = ["jaydiff*"]